I had a host that wasn’t backing up at all and found the following error message within the CrashPlan engine_error.log located in /usr/local/crashplan/log

From what I could tell it was related to a CentOS 6.x upgrade that may have set the noexec on /tmp which wasn’t set previously.

The error sees to be related to writing files to the /tmp directory, the following two websites I found by a simple Google search revealed this problem.

http://feeding.cloud.geek.nz/posts/crashplan-and-non-executable-tmp-directories/

CrashPlan Pro for Linux: Stuck at “Waiting for Backup” or “Connecting to Backup Destination”

You have to update the CrashPlan Java options to store its temporary that isn’t mounted as “noexec” by your system

Open up  /usr/local/crashplan/bin/run.conf and add the following to the end of SRV_JAVA_OPTS